Download The ImageJ User Guide

Process .
Noise .
Use Stack Histogram If checked, ImageJ will use the overall stack histogram instead of
individual slice histograms, that allow optimal adjustments for each slice alone. This
option may be specially relevant when performing enhancements based on a ROI.
See also: Brightness/Contrast. . . [C] , XIV Applying Auto Brightness/Contrast to Entire Stacks
26.6
Noise .
Use the commands in this submenu to add noise to images or remove it.
Process . Noise . : Salt and Pepper, Despeckle, Add Noise and Remove Outliers. . .
See also: RandomJ (Binomial, Exponential, Gamma, Gaussian, Poisson and Uniform) a Java
package for image randomization by Erik Meijering
26.6.1
Add Noise
Adds random noise to the image or selection. The noise is Gaussian (normally) distributed with
a mean of zero and standard deviation of 25.
26.6.2
Add Specified Noise. . .
Adds Gaussian noise with a mean of zero and a chosen standard
deviation.
26.6.3
Salt and Pepper
Adds salt and pepper noise to the image or selection by randomly replacing 2.5% of the pixels
with black pixels and 2.5% with white pixels. This command only works with 8–bit images.
Improved
in IJ 1.45m
26.6.4
Despeckle
This is a median filter. It replaces each pixel with the median value in its 3×3 neighborhood.
This is a time consuming operation because, for each pixel in the selection, the nine pixels in
the 3×3 neighborhood must be sorted and the center pixel replaced with the median value (the
fifth). Median filters are good at removing salt and pepper noise.
96
Latest revision: 2011/08/06